Air to air missiles on biplanes & synchronised gatlings

[zenrat]

Hence synchronisation as placing a Vulcan pod on the centreline in place of a torpedo would negate the weight & stresses somewhat.
Vulcans are electrically triggered so to synchronise one you'd "simply" need to have a system that broke the triggering circuit when a blade was going to be in the way.

If you do that, half the bullets will be going out the ejector port unfired.

Hmmm, lets see.
What's a "typical" prop spin at?  Googling says 2500 rpm for a light aircraft.
A Vulcan fires at 6000 rpm.
Thats 2.4 rounds per prop rotation or a round every 150 degrees.
Swordfish has a 3 bladed prop so that's a blade every 120 degrees.
Worst case is therefore a blade and a bullet would align every 600 degrees ejecting every 4th round.

However, if you slowed the vulcan to 5000rpm and it was timed right from the first shot you'd be firing 2 rounds per prop rotation and not ejecting any live rounds.  So ironically by reducing the rate of spin you'd actually increase the effective rate of fire.

Doesn't help with the recoil mind...

[zenrat]

Given that the AIM-9 weights in at a "whopping" 188lbs (85.3kg), a Swordfish would have no problem lugging them into the air.  Might even handle the launching of them, provided the fabric doesn't ignite in the rocket exhaust.  That'd shorten your crew's enthusiasm for getting involved in Air Combat Maneuvers.

Mk111 Stringbags had metal skinned lower wings specifically so they could fire rockets.

[Hobbes]

Hmmm, lets see.
What's a "typical" prop spin at?  Googling says 2500 rpm for a light aircraft.
A Vulcan fires at 6000 rpm.
Thats 2.4 rounds per prop rotation or a round every 150 degrees.
Swordfish has a 3 bladed prop so that's a blade every 120 degrees.
Worst case is therefore a blade and a bullet would align every 600 degrees ejecting every 4th round.

However, if you slowed the vulcan to 5000rpm and it was timed right from the first shot you'd be firing 2 rounds per prop rotation and not ejecting any live rounds.  So ironically by reducing the rate of spin you'd actually increase the effective rate of fire.

Good point, but what to do with the time when the barrels are accelerating to 5000 rpm? You might be able to wait until it's up to speed before feeding in any bullets, but then you'd have a large delay between pulling the trigger and the first rounds being fired.

[Old Wombat]

To reduce the rather high likelihood of the wings being ignited by the missiles' exhausts when firing the Sidewinders, sheath the lower wings in aluminium a few feet either side of the launch rails.

20mm cannon would be... interesting... to say the least, but, if you really, really must have a 20mm (or even a .303 minigun), I'd have a 3-barrel unit podded under the fuselage (or, for 2 units, 1 podded on either side of the engine) & geared directly to the engine so that every barrel fired every shot, each timed to fire into the free space in the propellor cycle. This way the rate of fire would be determined by the engine rev's. Problem with this system is that there would be the possibility of shooting off your prop at very high rev's, when the blades are moving too fast for the bullet to leave the barrel & pass through the arc before the following blade is in its way, given the constant firing point.

Alternately, you could use a modified & beefed up variation of the constant-speed-drive used to run the aircraft's power supply to drive the weapon, which would vary the triggering of the rounds slightly to compensate for the changing speed of the blades, or use a system similar to variable timing on a piston engine, where the points adjust with speed to fire the spark earlier in the cycle at high rev's.

Whichever possibility you look at or chose, even a single 20mm on a Swordfish is going to cause big problems due to recoil slowing the aircraft (possibly into a stall if fired too long) &, more importantly, causing serious structural damage every time it is fired.



Guy

[zenrat]

I'd assumed (based on the highly technical research method of watching Arnie movies) that when they went "guns hot" they spun the barrels up to speed and kept them rotating until they pulled the trigger at which point the rounds were fed in and the thing started firing.

Maybe i'll just mount the thing on the top of the upper wing like the Lewis gun on an SE5.
I can then put a pave knife pod underneath on the centreline...

[Old Wombat]

Maybe i'll just mount the thing on the top of the upper wing like the Lewis gun on an SE5.

Ah, instant Swordfish monoplane!



Guy

[PR19_Kit]

One of my Field Engineers used to work on the RNHF and often flew back seat in the Swordfish. He was the poor sap who had to hang onto the White Ensign that they flew from the cockpit during displays. He reckoned that the aircraft slowed by 10 kts when they used the larger of the two Ensigns so that was only flown on calmer days.

[NARSES2]

Dad reckoned Swordfish stopped in a headwind when landing on an Aux A.C and there's a anectdote in a book I have of one alledgedly going backwards in a very strong headwind and being overtaken by a seagull 

What is a "rotary Accles gun"?

Glad you asked mate, I had no idea

[jcf]

According to Rapid Fire by Tony Williams the M61A1 has a 26kW (34.85hp) drive motor and spins at
1,000 rpm(revolutions per minute).
Generating that level of electrical power in a Swordfish would be problematic.

The SUU-16/A gun pod uses a RAT (ram air turbine) to power the gun, which causes a delay
of about a second in spin-up time, and rate of fire falls below 6,000 rounds-per-minute if forward
speed falls below 650km/h.   

[Gondor]

The SUU-16/A gun pod uses a RAT (ram air turbine) to power the gun, which causes a delay
of about a second in spin-up time, and rate of fire falls below 6,000 rounds-per-minute if forward
speed falls below 650km/h.   

And a Swordfish is going to reach speeds over 650Kph is it?

Makes its use a little unlikely I think.

Gondor

[scooter]

Replace the Lewis or Vickers K gun in the rear cockpit with an M-1900 series Gatling gun, fitted out for .303 caliber?

[zenrat]

The SUU-16/A gun pod uses a RAT (ram air turbine) to power the gun, which causes a delay
of about a second in spin-up time, and rate of fire falls below 6,000 rounds-per-minute if forward
speed falls below 650km/h.   

And a Swordfish is going to reach speeds over 650Kph is it?

Makes its use a little unlikely I think.

Gondor

Are we back to ramjet biplanes again?


Did I mention it'll be on floats? 

[Old Wombat]

Floats? I'd seriously go for 2 fuselage-side mounted .303 miniguns, then, in a set-up similar to the one I described here earlier (see below). However, a single side-mounted 20mm might be possible using the same set-up.

...snip... I'd have a 3-barrel unit podded under the fuselage (or, for 2 units, 1 podded on either side of the engine) & geared directly to the engine so that every barrel fired every shot, each timed to fire into the free space in the propellor cycle. This way the rate of fire would be determined by the engine rev's.
...snip... use a modified & beefed up variation of the constant-speed-drive used to run the aircraft's power supply to drive the weapon, which would vary the triggering of the rounds slightly to compensate for the changing speed of the blades, or use a system similar to variable timing on a piston engine, where the points adjust with speed to fire the spark earlier in the cycle at high rev's.

To prevent the weapon spinning the entire time the aircraft is in flight a clutch system could be engaged to fire the weapon & disengaged when the pilot finishes firing. Wind-up speed would be about 0.1 seconds with the right design & a 2-part trigger pull could minimise ammunition wastage or the potential for shooting oneself down by unintentional shortening of the propellor blades.

This mechanical/mechanical-hydraulic system removes the need for an impossibly powerful generator to be fitted to the aircraft & leaves the underside of the fuselage free for a torpedo/Harpoon if required.

I still think you're going to need a bigger engine, though, to carry the floats, a 20mm cannon plus the other munitions.



Guy

[Weaver]

Re the Sidewinders, remember that you need a launch rail as well, which takes the combined weight up to approaching 250lb if I remember correctly. Still well within a Stringbag's weight limit, but one other thing that would worry me is possible aeroelastic effects. A Sidewinder is nearly 10 feet long, so if it starts to flutter it can generate some quite significant forces on the structure it's attached to. Of course it's normally attached to a nice strong metal wing, but I wonder whether a Swordfish's wing is braced to take those kind of twisting loads?

[Dizzyfugu]

You could also use a gatling gun with a pneumatic drive (Russian style). Much simpler, and even quicker to react/spin up.

Recoil-less, heavy calibre cannons are also a potential weapon if you want to go anachronistic. Not really air-to-air-weapons, but large tubes always look good and intimidating. In the pre-WWII-era, 80mm guns of this kind (single shot) were tested in the Soviet Union, and Germany had such things of up to 150mm caliber(!) in the pipeline, reaching more or less through the whole aircraft. I think UK also had such things on the table, at least in the early jet age, coupled with a drum magazine.